The purpose of this study is to determine the effectiveness of a 24-week home-based, moderate intensity walking program in alleviating common physical and psychological health symptoms and improving physical fitness and exercise behavior in sedentary employed midlife women. The specific aims are: (1) to compare women's health symptoms, physical fitness, and exercise motivation after completing the walking program with their own preprogram measures and those of a control group of nonexercisers; (2) to identify relationships among the amount of change in pre- to postprogram health symptoms and physical fitness; (3) to compare health symptoms, physical fitness, and exercise motivation measures 24 weeks after completing the walking program with immediate postprogram scores; and, (4) to determine the effect of the walking program on the relationships between health symptoms and their known correlates (i.e., role quality, menopausal status, menopausal attitude). Subjects will be 174 apparently healthy, sedentary, nonobese women aged 40-60 who are experiencing health symptoms common to midlife women and who are not on HRT, are not pregnant, and have not had a bilateral oophorectomy. Volunteers will be sought from large organizations with employees representing diverse ethnic and socioeconomic groups. Subjects will be randomly assigned to an experimental or control group in an experimental crossover design. The proposed intervention will require no equipment and will be carried out at times and locations convenient to the individual women. Walking will be prescribed at 50-74% HRmax reserve and progress from 20 to 30 minutes of continuous walking 4 times per week over a 24-week period. At the end of 24 weeks, the control group will begin the same program, and the experimental group will be monitored for 24 weeks more to determine whether they continue the walking program. Adherence during the intervention phase will be assessed by exercise logs and wireless heart rate monitors and during the continuation phase by exercise logs only. Every 2 weeks the experimental group will complete health symptoms measures and receive feedback and support for adherence and progress. The control group will also complete the health symptoms measures every 2 weeks to monitor symptoms and to control for contact with the experimental group. Other measures administered to both groups at 0 and 24 weeks will address factors known to influence symptoms at midlife (menstrual history; hormonal assays of follicle-stimulating hormone, estradiol, estrone; attitude toward menopause; role quality); exercise motivation (exercise self-efficacy, exercise self-determinism); and physical fitness, including aerobic fitness (maximal exercise test), body composition (body mass index, dual-energy x-ray absorptiometry), and flexibility (digital inclinometer). Exercise motivation, physical fitness, and health symptoms will be reassessed at 48 weeks. The walking program is the independent variable; dependent variables are health symptoms, fitness, exercise motivation, and continuation. Planned analyses include ANOVA, repeated-measures ANOVA, paired comparison t tests, and multiple regressions. Positive outcomes will support the effectiveness of home-based, moderate intensity exercise for nonpharmacological relief of health symptoms.